1. Technical Field
The present invention relates to a device, system, program and method for performing security communication and output, and particularly to a security output device, a security output system, an output device control program and storage medium, and a security output method that are suitable for improving security in an environment used by unspecified multiple host terminals.
2. Related Art
There is a need for a technique of allowing only authorized access to a network printer used via a network and eliminating unauthorized access to the network printer. When using the network printer, in some cases, only authorized access should be accepted. For example, in the case of providing a charging service, first, a printer server or the like should perform necessary charging processing in response to a print request and then the network printer should start printing. Therefore, if the network printer accepts a direct print request for which charging processing has not been performed, charging cannot be done.
As techniques of eliminating unauthorized access, for example, there have been an image forming device disclosed in Japanese Patent Application Publication 2003-114789 and a printer device disclosed in Japanese Patent Application Publication 9-259351.
According to the technique disclosed in Japanese Patent Application Publication 2003-114789, identification information representing each user or host terminal is stored into a storage unit in advance. Identification information is acquired from received data, and it is judged whether or not a user or host terminal represented by the acquired identification information is included in the users or host terminals represented by the identification information in the storage unit. On the basis of the result of this judgment, whether print processing should be executed or not is determined.
The technique disclosed in Japanese Patent Application Publication 9-259351 includes a charging device for limiting users, and a network printer. The charging device allocates ID when a coin is put therein. When starting the printing, a user sends the allocated ID together with print data. The ID to be sent is sent in the form of code that can be decoded by the network printer. On receiving the print data, the network printer judges whether it is an ID confirmation command or not. If the ID is not authenticated, the network printer will not accept the remaining print data. Therefore, an ID confirmation command is sent from a host terminal before all the other commands. If an ID confirmation command is received, the network printer checks whether it is an ID to be authenticated or not, and then authenticates the sent ID with the stored ID.
However, in the technique disclosed in Japanese Patent Application Publication 2003-114789, in a situation where the network printer accepts accesses from unspecified multiple host terminals, it is difficult to perform setting of host terminals in the network printer in advance.
In the technique disclosed in Japanese Patent Application Publication 9-259351, since the allocated ID is sent together with the print data, if a malicious user analyzes the ID creation rules, unauthorized access may be made.
Thus, both of the techniques disclosed in Japanese Patent Application Publication 2003-114789 and Japanese Patent Application Publication 9-259351 have a problem of insufficient security.
Such a problem may occur not only in the case of performing printing by the network printer but also in other cases, for example, where a display device such as a projector or LCD (liquid crystal display) is connected to a network to perform display on the display device.